Industrial Mineral Potential of Pegmatites in the Lokoja Area (Sheets 247nw and 247sw), North-Central Nigeria

Abstract

Field geological mapping and compositional (mineralogical and chemical) evaluation of the pegmatites in the Lokoja area (Longitudes 6º 37′ 00″ E and 6º 47′ 00″ E and Latitudes 7º 42′ 00″ N and 7º 51′ 00″ N) were carried out to evaluate the industrial mineral potential of the pegmatites. The pegmatites occur in tabular forms as dyke-like structure and veins of large interlocking crystals of quartz, feldspars and mica and distributed within two host rocks (migmatite and granite gneiss). Petrographic analysis (thin section) of eight of the pegmatite samples revealed that the pegmatite has a modal composition of plagioclase (26.25%), orthoclase (17.89%) and microcline (36.75%) which are raw materials used in glass and ceramics production, quartz (8.1%) and biotite (11%). twelve samples of the pegmatite were analysed using the X-ray Fluorescence spectrometry and the chemical composition obtained for silica (SiO2) and alumina (Al2O3) content of 67.47 wt % and 14.01 wt % respectively. The alumina (Al2O3) is greater than the alkalis (Na2O + K2O + CaO) in the samples with an average value of 1.43% which indicates that the pegmatites are siliceous and peraluminous. The pegmatite is dominated by feldspars which are raw material used in ceramics and glass production and the chemical composition of the major element of the pegmatites of the study meets up with the Indian standard requirement suitable for use in various industries (glass, whiteware and pottery) and also meets the requirement for sanitary ware and ceramic-tiles industry as required by the British standard.